Reproduction will be analyzed in Drosophila, using a combination of genetic, molecular, behavioral, and neurobiological approaches. Manipulation of the pertinent genes--in their normal and mutant forms--plus detailed analysis of the phenotypes influenced by these factors is considered primarily from the standpoint of how these diptera control their complex actions; but these kinds of genetically induced defects in neural function also are relevant to the neurogenetics of higher brain functions in other organisms. Specifically, mutations causing ABERRANT AUDITORY COMMUNICATION--cacophony, dissonance, and Choline- acetyltransferase-TS--will be studied, in terms of where and how these variants disrupt CNS structure or function; and with regard to isolation and analysis of cloned sequences corresponding to those loci (including where the primary gene products are expressed). New "wing vibration" mutants will be screened for (in some cases to expand the array of variants at known loci such as cac and diss). A RHYTHMIC ELEMENT of acoustic communication will be further investigated, primarily with reference to the neural substrates of these oscillations (e.g., as affected by nerve-conduction mutations). OLFACTORY COMMUNICATION in reproduction will be more deeply delved into, in regard to reception and processing of the relevant pheromones, studied physiologically at the periphery and more centrally with respect to a mutant--olfactory-D--that essentially fails to respond to these chemosensory cues. The fruitless mutation, which (at least) causes aberrant production of pheromones, will be analyzed--including molecular approaches to tue locus; this will allow questions to be asked about where and when the gene is expressed, to provide clues on the etiology of the "syndrome" of reproductive abnormalities induced by fru. CONDITIONED COURTSHIP--known to involve the "processing" of both auditory and olfactory stimuli--will be dissected genetically, mostly by determination of the neural substrates of three specific learning/memory mutants that are aberrant in these experience-dependent aspects of male/female interactions; correlations will be made with emerging knowledge (from other investigators) on where the products of the relevant genes are expressed in the animal's CNS.